Train control system



July 5; 1932. re. WILLIAMSON TRAIN CONTROL SYSTEM Original Filed Nov. 10, 1926 4 6 7 1) VOlT/FGE avwwntoz Patented July 5, 1932 UNITED" STATE-1S;

TPATENT orl-"lcef -AB-BA e. WILLIAMSON; or CARNEGIE, PENNSYLVANIA; ASSIGNOR TO THE union SWITCH & SIGNAL COMPANY, OF PENNSYLVANIA SWISSVALE, PENNSYLVANIA; A CORPORATION or TRAIN CONTROL SYSTEM.

Original application filed November 10, 1926, Serial No. 147,403; Divided and.

November '14; 19 30.

The present invention relates to train-control systems, the trainor traflic controlling means being of any suitable character such as signals or retarding or stopping devices or both, and has forits main object and .tea-

Fig. 2 is a diagrammatic view ofa traincarried equipment disclosing oneform ofthe' invention; and

Fig. 3 is a graph showing a characteristic curve of a gas-containing electron tube.

Carried by the train" is a traffic-governing relay 24 which may be biased in any of the ways kn own in the art. such as those disclosed in application Ser. No. 147,403 previously referred to, to assume one condition" when current of an intermediate value (for instance an average value of 0.40) is flowing through its coils. and to assume another condition when current is either increased (as to the value of 1.00) ordecreased with respect to saidintermediate value. Inthe present case, relay 24 is provided with a neutral armature 28 that remains in its up position so long as current of an intermediate orof greater value is flowing in the coilsof 24, and that drops when current is absent or falls belowsaid intermediate value. Relay 24 is further providedwith a polarized armature 30 that assumes a right hand position (as viewed in Fig. 2) as long as current of an intermediate value is flowing in the coilsof 24, and that assumes a left handposition when the current flow in the coils of 24 is either increased or decreased with respect to said intermediate value. Carried by the train is also a gas-containing electron discharge device ortube E which acts as a detector and -Serial No. 495,724.

' tuning condenser 222 spans-thewires 219 and 220. :The filament is heated by battery 211 clpnnectedby wires 212 and 213 to the filament 3 wire 217 5 relay 24, "wire' 2l8 plate P filament F and wires 213 and 215'back to battery 216. a Thecircuit through the train controlling device or trainindicating device 33 consists of battery216, wire 217 neutral armature 28 0f relay 24, polarized armature 30 of '24, wire 225. magnet of 33, and wires to battery 216.

It iswell known that when traces of certain 226 and 215 back Theplate circuit consists of battery 2165 this application filed gases or metallic vapors are'introduced into result in greater effectiveness ofthe tube as a detector; In Fig. 3 is shown a characteristic curve for a tube containing sodiu m -pota s sium alloy" vapor, and it will be noted thatat its upper end the curve takes a sharp bend indicating the saturation point. N, indicates the saturation point and this point is reached at zero-grid potential with respect to the fila- .ment. and therefore any increase in the positivepotential of the, grid with respectto the filament does not increase the value. of th plate current.

Let us assume that the parts are so are; ranged and .theplate and filament voltages aresoselected'that, when no voltage is impressed on coil 1, the operating point .on the fcurve'of 3 is N Then when an alternating current is induced in coil 1 the voltage applied to the grid during the positive half cycle 6) will not increase the flow of current in the plate circuit but when the negative potential is applied to the grid during the negative half cycle (-e) the flow of currentin the plate circuit will be: materially reduced, the reduction being indicated by 2' Thus an intermediate value, say 0.40 will be estab-lishedwhen current is present: in the track circuit, whereas when no current is the source ofcurrent on thetrain fails or a circuit becomes so disarranged that tube E' fails to properly" function and theplate current falls to a low value or to Zero, this condition is indicated by the circuit through train controlling n1agnet33'bein ruptured by the polarized armature and also y neutral armature 28. V

As shownin-Fig. 1', 55 and 56- represent the two trafiic rails arranged into blocks A, B and G by means of insulation 3. Thenormal direction of trafiic through said blocks is indicated by the arrow between the rails.

' At the ingoing" end of each block is a relay,

marked 148'in block (3' and 148 in block B, connected across the rails by suitable leads, and at the outgoing end of each block in a track battery 155' -which is connected across the rails by leads 150 and 156. The function of this battery" is merely to energize a track relay like 148it is not sufliciently powerful to control the train. The train control current is here supplied from generator 51, in this instance of the alternating current type, byway of line wires 52 and 53 to a track transformer associated with each block. Takingblock Bas an example, it will be seen that the primary of track transformer- 101 is connected by wires 143 and 144 to line wires 52 and 53. Secondary 145 of the track transformer is connectedto rail-56' by wire 146, armature 147' (of the track relay of the block in advance) contact 149 and wire 150, and is connected'to rail 55 by wire 152, re-

sistance 153 and wires 154 and 156. The

' function of resistance 153 is topre vent secondary 145 from short circuiting the battery.

An impedance coil-157 is interposed in wire 156 to choke back the flow of alternating current so that it will not ass to the battery. 7

The power supplied'from secondary 145 to the rails is of such amplitude that the pick-u circuit on the train will be energized; t

will now be understood that the presence, in the rails, of current from 145 will choke down the current in the train-carried charged circuit so that it willhave the intermediate value of 0.40, and therefore the circuitunder control of relay 24 will remain closed.

If block 0 be unoccupied, then track relay 148' will be energized and train-control current from secondary 145 will pass to the rails of block B, with the result that it a train enters block B from block A, such train will have its cab equipment controlled thereby giving a clear indication. On the other hand if'blockClis occupied when a train enters block B from A, then such train, entering block B from A, will'receive no train-control current'because trackrelay 148 of block C will have beendeenergized by the train in block C thereby dropping armature 147 and opening the circuit from secondary 145 to rails. The effect of this condition on the train; is that 'a current value of 1.00 is established in the charged circuit passing through relay 24', and that therefore the circuit through33 is ruptured.

It will further be observed that, although the presence of a train in block C deencrgizes track relay 148 and thus cuts oif train-control current from the rails of block B, track relay 148 of block B will nevertheless remain energized (provided B is unoccupied) by reason of current flow from battery 158 so that a train in block A will not be controlled by a train in block G.

If a train enters a block already occupied by anothertrain, then the train so entering will be subject to no train-control current.

I claim:

1. A train control system including: a

trackway circuit having a source of current, a train,- a train-carried closed circuit having asource ofcurrent, a train-carried receiving circuit in an inductive relation with said track-way circuit and responsive to current flowing! therein, and a train-carried gas-containing electron discharge device included in said receiving circuit and controlled thereby to establish a predetermined value of direct current flowing in the managed circuit in response to a flow of current in the trackway circuit.

2. A train control system including: a trackway circuit having a source of current, a train-carried circuit in an inductive relation' with said trackway circuit and 'responsive to current flowing therein, a traincarried charged circuit having a flow of current. of a given value, and a train-carried gas containing electron discharge device COIL- trolled by. the receiving circuit to lessen the flowof current in the charged circuit in response to a flow of'current in the track circuit; l 3. A train control 7 system including: a trackway circuit having a source of current,

a train-carried pick-up circuit in an inductive relation to said trackway circuit and responsive to current flowing therein, a train-. carried gas-containing electron discharge device, said device having a grid that is;

included in the pick-up circuit and that is rendered alternately positive and negative as long as current is induced in the pick-up circuit by current flow .in the trackway circuit, and a train-carried charged circuit including the electron discharge device and having a flow of current of a given value, said value being decreased'when the grid is rendered negative.

4. A train control system including: a trackway circuit having a source of current, a train, a train-carried gas-containing electron-discharge device having a plate, a grid 7 and a filament, a train-carried closed circuit including the plate and filament, a low voltage source of current in said closed circuit to supply substantially its max mum flow when the voltage of the grid with respect to the filament is substantially at zero, and

\ a receiving circuit on the train, including the grid and filament, in an inductive relation with said trackway circuitand responsive to current flowing therein to alternately render the grid positive and negative with respect to the filament whereby the flow of current in the closed circuit is substantially decreased below said maximum when the grid is rendered negative but not substan tially increased above said maximum when the grid is rendered positive.

5. A train control system including: a

trackway circuit having a source of current, a train, a train-carried electron-discharge device having a plate, a grid and a filament, a train-carried closed circuit including the plate and filament, a source of current in said closed circuit to supply substantially its maximum flow when the voltage of the grid with respect to the filament is substantially at zero, and a receiving circuit on the train,

' including the grid and filament, in an inductive relation with said trackway circuit and responsive to current flowing therein to alternately render the grid positive and negative with respect to the filament whereby the flow of current in the closed circuit is substantially decreased below said maximum whenthe grid is rendered negative but not substantially increased above said maximum when the grid is rendered positive.

Signed at Swi'ssvale, in the county of a V Allegheny, and State of Pennsylvania, this 13th day of November, 1930.

ABBA G. WILLIAMSON. 

